Barrel surrounding mount for operating drum of externally powered automatic gun



Feb. 14, 1967 c. E. LANlzzANl 3,303,744

BARREL SURROUNDING MOUNT FOR OPERATING DRUM OF EXTERNALLY POWERED AUTOMATIC GUN Filed DGO. 14, 1962 4 Sheets-Sheet l TUIFNEYS Feb. M, i967 c. E. LANlzzANl 3,303,744

BARREL SURROUNDING MOUNT FOR OPERATING DRUM OF EXTERNALLY POWERED AUTOMATIC GUN Filed D60. 14, 1962 4 Sheets-Sheet 2 ATTGRNEYS Feb. 14, 1967 c. E. LANlzzANl 3,303,744

BARREL SURROUNDNG MOUNT FOR OPERATING DRUM OF EXTERNALLY POWERED AUTOMATIC GUN Filed DSC. 14, 1962 4 SheetS-Sheeb 5 ATTRNEYS Feb. 14, 1937 c. E. LANIZZANI 3,303,744

BARREL SURROUNDING MOUNT FOR OPERATING DRUM OF EXTERNALLY POWERED AUTOMATIC GUN Filed Dec. 14, 1962 l 4 Sheets-Sheet 4 United States Patent O 3,303,744 BARREL SURROUNDNG MOUNT FOR OPERAT- ING DRUM OF EXTERNALLY PGWERED AUTO- MA'IIC GUN Charles E. Lanizzani, Stafford, Conn., assgnor to the United States of America as represented by the Secretary f the Army Filed Dec. 14, 1962, Ser. No. 246,862 6 Claims. (Cl. .S9-161) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to automatic guns which can be operated at different rates of re and is more particularly directed to a gun of this type in which the operating parts thereof are actuated by a rotating drum powered by an electric motor.

Inasmuch as current military planning contemplates the use of a universal type of machine gun which will be equally effective against such diverse targets as aircraft, ground vehicles, or personnel, it is essential that these guns possess suitable means for increasing or decreasing the rate of fire in a predetermined manner in order to permit a rapid shift in use from one type of target to another. lt has been found that the required changes in the rate of tire can best be accomplished if the feeding, locking, and ring cycles of the gun are controlled by separate cams provided in a rotatable drum driven by an external source of power having a variable output.

While this concept has been satisfactorily applied to a gun in which a helical cam on the exterior periphery of the drum is utilized to reciprocate a single barrel between tiring and feeding positions, certain problems have arisen due to the erratic rotation of the drum encountered during relatively prolonged bursts of fire.

A careful analysis of this gun design has indicated that the uneven rotation of the drum is largely due to lthe fact that the location thereof below the axis of the barrel creates a couple which imparts torsional forces to the bearings on which the drum is rotated. Furthermore, another factor which contributes to the undesirable variation in the rotational velocity of the drum is the abrupt change in the forces applied thereto as the followers, which engage the various cam tracks therein, leave the dwell portions thereof and move into positive engagement with the cam portions. Still another factor responsible for the erratic operation of the drum, but to a lesser degree than those previously mentioned, is the excessive transfer of the heat in the barrel to the drum bearings and the consequent binding effect thereon. Of much smaller but still material significance is the exposed location of the various cam tracks formed in the drum which permits the accumulation therein of dirt or other foreign material capable of interfering with the desired smooth transfer of the rotational velocity of the drum to the corresponding operating assemblies in the gun.

lt is, therefore, a general object of this invention to provide an automatic machine gun adapted to be cycled by an operating drum which will not be subject to undesirable variations in the rotational velocity thereof during sustained fire.

It is an important object of this invention to produce a gun of the aforesaid type wherein the operating drum is specically located to virtually eliminate the transmission of torsional forces thereto.

A further object of the present invention lies in the provision of an automatic machine gun, as aforesaid, wherein the bearings on which the operating drum is mounted are substantially isolated from the heat generated in the barrel by sustained automatic fire.

3,333,744 Patented Feb. 14, 1967 Maice Still another object of this invention is to provide an automatic machine gun, as aforesaid, wherein the connection between the drive motor and the operating drum is geared in a manner which actually enhances the ability of the latter to overcome the inertial resistances of the feeding, locking, and firing functions encountered in each cycle of operation.

A secondary object of this invention is to provide an automatic gun, as aforesaid, wherein the functions of feeding, locking, and firing are sequentially and independently controlled by suitable cam tracks which are disposed on or in the operating drum in such a manner as to prevent the accumulation of dirt or other deleterious foreign matter.

In accordance with the teachings of the present invention, the torsional forces heretofore encountered during the automatic fire of those guns in which the functions of feeding, locking, and firing are controlled by a motor driven operating drum can be virtually eliminated by locating the latter so that the central axis thereof coincides with the longitudinal axis of the barrel. This desirable relationship is best achieved by forming the drum as a hollow cylinder and mounting such cylinder for symmetrical rotation about a tubular member which extends forwardly from the receiver to surround the barrel. In this arrangement, the helical cam track utilized to reciprocate the barrel is formed about the interior periphery of the hollow drum and the cams responsible for feeding, locking, and firing are provided on a ring gear member which closes the rear end of the drum and also operates as a flywheel capable of overcoming the inertia forces encountered in the starting and stopping of the feeding, locking, and firing mechanisms of the gun. In addition, the forward end of the operating drum is also closed to completely seal the interior thereof against the entry of dirt or other foreign matter.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. l is a side view of the gun of this invention with the cartridges normally disposed in the feed tray being removed to show the barrel in battery position;

FIG. 2 is a sectional view taken along line 2-2 of FIG. l to show the manner in which a linked cartridge belt is fed into the gun to position the leading cartridge in firing position;

FIG. 3 is a longitudinal section of the gun with the housing for the tiring mechanism partially broken away to show the hammer in the fired position and the barrel partially broken away to show the fired cartridge case;

FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. 3 to show the firing and locking cams in the drum; and

FIG. 5 is a cross-sectional view taken along line 5 5 in FIG. 3 to show the feeding cam in the drum.

As illustrated in the drawings, the gun of the present invention includes a substantially rectangular receiver 12 provided with a forwardly opening central bore 14 for slidably receiving a reciprocal barrel 16. Receiver 12 is forwardly extended in coaxial alignment with bore 14 to form a tubular housing 18 concentric with barrel 16. A hollow cylinder 20 is rotatably mounted on housing 18 by means of front and rear roller bearings 22 and 24, respectively, to serve as an operating drum for controlling the feeding, locking, and firing functions of the gun as will be lhereinafter shown. A bracket 26 projects upwardly from receiver 12 and serves to mount an electric drive motor 28 capable of a variable output which is transmitted to drum 20 by a gear assembly 30 engageable with a ring gear 32 forming a portion of a ywheel 34 secured to the rear end of drum for rotation therewith.

A central portion of barrel 16 is diametrically increased, as shown at 36, to provide a bearing surface therefor in housing 18. Forwardly of increased diameter portion 36 is a base 37 for an upwardly projecting post 38 terminating in a roller 40 engageable in helical cam track 42 formed about the interior periphery of drum 20. The top of housing 18 is longitudinally slotted, as indicated at 44, to provide a passage for the longitudinal travel of base 37 during the reciprocal movement imparted to barrel 16 by the rotation of drum 20. The forward end of slot 44 is enlarged to receive an arcuate spacer 46 in contact with the upper surface of barrel 16 and of sufficient height to provide contact with both roller bearing 22 and barrel housing 18. A ring 48 depends from spacer 46 and is positioned within the interior of housing 18 to encircle barrel 16 and provide support thereto during the longitudinal reciprocation thereof.

An annular plate 50 is securely fitted into the forward end of drum 20 and is centrally provided with a circular recess 52 for seating roller bearing 22 therein which is, in turn, retained in place by an annular cap 54 secured to the forward end of barrel housing 18 by threads 56. At the rear end ofdrum 20, the interior diameter thereof is reduced, as shown at 58, to seat roller bearing 24 in coaxial relation with roller bearing 22 for engagement with the exterior periphery of housing 18. Longitudinal displacement of roller bearing 24 is prevented by opposite annular shoulders and 62 respectively provided in housing 18 and drum 20.

Flywheel 34 is formed with an exteriorly threaded portion 64 `of reduced diameter disposed forwardly of and immediately adjacent to ring gear 32 and is further provided with a forwardly projecting circular portion 66 which serves as the closure for the rear end of drum 20. Circular portion 66 is radially slotted, as shown at 68, to engage a correspondingly shaped lug 70 formed in the interior of drum 20 for insuring the proper radial orientation of flywheel 34 relative thereto. Flywheel 34 is releasably secured to drum 20 by an interiorly threaded collar 72 simultaneously engageable with threaded portion 64 on ywheel 34 and an outwardly projecting flange 74 'at the rear end of drum 20.

As best shown in FIG. 5, the rear face of flywheel 34 is formed with a cam track 76 having a circular dwell por- 'tion 78 and an eccentric cam portion 80 for controlling the feeding of a linked belt of cartridges 82 into a transverse feedway 84 in the rear of receiver 12. A feed tray 86 (FIG. 2) is tixedly secured to the side of receiver 12 in coaxial alignment with feedway 84 to complete the passsageway for the linked cartridge belt. The floor of feedway 84 is grooved along the junction with the rear end wall thereof, as shown at 88, to engage the annular rim of each cartridge 82 and guide such cartridge into the proper firing position thereof. The bottom of feed tray 46 is suitably slotted, as indicated at 92, to accommodate a reciprocal feed pawl 94 pivotally secured to the upper l'end of a feed lever 96. A bifurcated bracket 98 is secured to the underside of receiver 12 for rotatably supporting a rod whose rear end is .fixed to the lower end of feed lever 96. The forward end of rod 100 is similarly fixed to the lower end `of a follower arm 104 on the upper end of which is provided a roller 106 for engagement in feed 'cam track 76 in iiywheel 34.

Thus, as drum 20 is rotated by drive motor 28, each ycartridge 82 in the linked cartridge belt is successively advanced into firing position in feedway 84 to eject the previously fired cartridge case therein. Flywheel 34 is, of course, so .oriented in drum 20 that the dwell portions of cam tracks76 and 42 prevent movement of barrel 18 during the feeding advance of lthe cartridge belt and also prevent the feeding movement of the cartridge belt during the reciprocation of barrel 18. Chambering of the leading cartridge 82 in Ithe belt is accomplished as barrel 18 is moved rearwardly into battery position and is halted there- 4 in upon contact with the annular rim 90 of such cartridge. Since the contact between the increased diameter portion 36 of barrel 16 and the interior periphery of housing 18 provides a piston and cylinder relationship, the circumference of barrel 16 is longitudinally slotted, as shown at 107, at a plurality of areas to minimize the compressive effect thereof on the air within barrel housing 18.

Locking of barrel 18 in battery position is accomplished by a locking block 108 provided with a rearwardly projecting roller 110 at the upper end thereof slidably seated in a substantially circular cam track 112 formed into the front face of flywheel 34 as best shown in FIG. 4. The upper portion of cam track 112 is formed with oppositely disposed cam slopes 114 which are spaced apart to insure that barrel 18 is properly locked during the entire firing operation. Locking block 108 is slidably mounted in a suitable slot 118 passing through the top of barrel housing 18 and is arranged to be cammed into and out of a correspondingly located annular locking groove 120 in barrel 16 by cam slopes 114 which are located in flywheel 34 so that contact thereof with follower roller 110 occurs while both the cartridge belt and barrel 18 are stationary. The inner periphery of flywheel 34 is provided with a protruding cam segment 122 located immediately below cam slopes 114 and in concentric alignment with the portion of cam track 112 therebetween. As best shown in FIG. 4, the arcuate extent of cam segment 122 issuch that the ends thereof thereof are disposed inwardly of cam slopes 114 to insure that the camming action thereof is limited to the period in which barrel 16 is fully locked. Firing of the chambered cartridge 82 is accomplished by an elonagated lever 124 pivotally mounted in receiver 12 to lie immediately above barrel housing 18. The forward end of lever 124 is engageable with cam segment 122 during rotation .of drum 20 while the rear end of lever 124 is extended into the hollow interior of a housing 126 suitably secured to the rear end of receiver 12. A sear 128 is pivotally mounted within housing 126 to engage a cooking notch 130 formed in a hammer 132 pivotally mounted to the floor of housing 126. As the forward end of lever 124 is depressed by firing cam 122, the corresponding movement Vimparted to the rear end thereof lifts sear 128 to release hammer 132 for impact with a firing pin 134 slidably seated in a central counterbore 136 through the rear end wall of receiver 12.` The underside of motor bracket 26 is suitably undercut, as indicated at 137, to provide for this pivotal movement of firing lever 124.

Thus, the entire operation of the gun is completely dependent upon the continuous rotation of drum 20 which is, in turn, driven by motor 28 whose speed can be quickly and easily varied in accordance with the type of target at which the gun is to be aimed. Since the major gun assemblies are specifically located to position the center of gravity in substantially close relation to the axis of barrel 16, and since drum 20 is rotated about an axis which coincides with the barrel axis, little or no torque is transmitted to the front and rear trunnions 138 and 140 by means of which the gun is adapted to be mounted in a vehicle or aircraft. The resulting freedom from vibration during relatively long bursts of fire is particularly valuable in securing increased hit probability. In addition, the reduced torque permits the utilization of lighter and less complex mounts which is especially desirable when the gun is mounted in aircraft.

Furthermore, the concept of mounting drum 20 for rotation about an axis coincident with the barrel axis became a practical possibility as a result of providing the interior of drum 20 with front and rear roller bearings designed to ride about the exterior periphery of the barrel housing 18 which is spaced from barrel 16 except for limited support areas in the vicinity of the roller bearings. Such design minimizes the flow of heat thereto from barrel 16 and, consequently, eliminates any binding thereof even under the extremely high temperatures encountered upon prolonged firing.

Since the rotation of drum does not result in any substantial torque on the gun or mount therefor, the ywheel 34 utilized to transmit the driving forces .of motor 28 to drum 20 may be of substantial weight. This factor virutally eliminates any variations in the rotational velocity of drum 2li at the particular instances at which barrel roller 46, feed roller 106, locking rollers 110, and firing lever 124 engage with their respective operating cams.

Another desirable feature provided by the utilization of cam tracks within the interior of a closed hollow drum 20 is the prevention of dirt accumulation therein which could interfere with the smooth operation of the major assemblies in the gun. Although the feed cam track 76 at the rear end of drum 2i) is partially exposed, the location thereof beneath receiver 12 aids in preventing any Vappreciable accumulation of foreign matter therein.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1. ln an automatic gun having a receiver with a forwardly opening `bore in rearward communication with a transverse feedway for the passage of a linked belt of cartridges, the combination of a barrel slidabiy disposed in the receiver bore for reciprocal movement into and out of ybattery position, a tubular housing extending forwardly from the receiver to sur-round said barrel in spaced relation thereto, a hollow cylindrical drum rotatably mounted on said housing in axial coincidence with said barrel therein, a follower projecting outwardly from said barrel, cam means in the interior of said 4drum engageable with said follower on said barrel, and means for continuously rotating said drum to reciprocate said barrel for successively chambering each cartridge in the ,belt during rearward @movement of said barrel into battery position.

2. in an automatic gun having a receiver with -a forwardly opening bore in rearward communication with a transverse feedway for the passage of a linked belt of cartridges, the combination of a barrel slidably disposed in the receiver bore for reciprocal movement into and out of battery position in which the leading cartridge in the feedway is completely chambered thereby for firing, a tubular housing extending forwardly from the receiver to surround said `barrel in spa-ced relation thereto, a hollow cylindrical drum having front and rear roller bearings therein for rotatably mounting said drum on said housing in axial coincidence with said barrel therein, a follower projecting upwardly from said barrel through said housin-g, helical cam means in the interior of said `drum engagea'ble with said follower on said barrel, means for continuously -rotating said drum to reciprocate said barrel for successively chambering each cartridge in the belt, and cam means in said drum for locking said barrel to the receiver during the battery position thereof.

3. The combination defined in claim 2 wherein said means for continuously rotating .said drum comprises a ring gear ysecured to the rear face of said drum, a drive motor mounted to the receiver, and gear ymeans for connecting said drive motor to said ring gear.

4. In an automatic gun having a receiver with a forwardly opening bore in rearward communication with a transverse feedway for the passage of a linked belt of cartridges, the combination of a barrel slidably disposed in the receiver ibore for reciprocal movement into and out of the feedway for charnibering the leading cartridge therein, a tubular housing extending forwardly from the receiver to surround said .barrel in spaced relation thereto, a hollow cylindrical drum having an annular -fr-ont cover with a forwardly opening circular recess therein, said drum also hav-ing a rearwardly disposed internal reduced diameter portion in coaxial alignment with said circular recess, first and second roller bearings respectively seated in said circular drum recess and in said reduced diameter portion for rotational engagement with the exterior periphery 4of said barrel housing whereby said drum is positioned in axial coincidence with said barrel, a ring gear secured to the rear end of said drum in bearing relation with the exterior periphery of said barrel housing, a follower iprojecting upwardly from said barrel, said housing having a longitudinal slot along the top thereof for passage of said barrel follower, a helical cam track about the inner periphery of said drum engageable with said barrel follower, drive means engageable with said ring gear for continuously rotating said drum to impart reciprocal movement to said barrel whereby each cartridge in the linked belt is successively chambered thereby, means for locking said barrel to the receiver during the eriod in which each cartridge is fully chambered, and a cam track in the rear face of said ring gear for actuating said barrel locking means.

5. The combination defined in claim 4 wherein said barrel is formed with an annular locking groove and said barrel locking means comprises a vertical lock slidably disposed in said barrel housing for movement int-o and out of engagement in said barrel locking groove, and a roller extending rearwardly from said lock to engage in said cam track in the rear face of said ring gear.

6. in an automatic gun having a receiver with a forwardly opening bore in rearward communication with a transverse feedway for the passage of a linked belt of cartridges, the combination of a barrel slidably disposed in the receiver bore for reciprocal `movement into and out the feed for chambering the leading cartridge therein, a tubular housing extending forwardly from the receiver to surround said `barrel in spaced relation thereto, said barrel having an enlarged diameter portion in slidable hearing relation with the interior periphery of said housing, a hollow cylindrical drum having an annular piate secured to the forward end thereof and a forwardly opening circular recess centrally formed in said plate, a first annuiar roller bearing seated in said circular recess, said drum having an internal reduced diameter portion adjacent the rear end thereof, a second annular roller hearing seated in said reduced diameter portion in axial alignment with said first roller bearing, said roller bearings `being thereby positioned to mount said drum on said barrel housing for rotation about an axis coincident with the axis of said barrel therein, a ring gear secured to the rear end of said drum in bearing relation with the exterior periphery of said barrel housing, a follower projecting upwardly from said barrel immediately forward said enlarged diameter portion thereof, said barrel housing having a longitudinal slot along the top thereof for passage of said follower during the reciprocal movement of said barrel, a helical cam track formed in the interior periphery of said drum for engagement with said 4barrel follower, drive means engageable with said ring gear for continuously rotating said drum to impart reciprocal movement to said barrel whereby each cartridge in the linked belt is successively chambered thereby, and individual cam means in said ring gear for successively actuating the cartridge feeding, barrel locking, and firing operations of the gun, said ring gear being of sufficient weight to act as a liywheel for minimizing the forces encountered in the initiation and cessation of each operating function of the gun.

No references cited.

BENJAMIN A. BORCHELT, Primary Examiner.

SAMUEL FEINBERG, Examiner.

F. C. MATTERN, S. C. BENTLEY, Assistant Examiners. 

1. IN AN AUTOMATIC GUN HAVING A RECEIVER WITH A FORWARDLY OPENING BORE IN REARWARD COMMUNICATION WITH A TRANSVERSE FEEDWAY FOR THE PASSAGE OF A LINKED BELT OF CARTRIDGES, THE COMBINATION OF A BARREL SLIDABLY DISPOSED IN THE RECEIVER BORE FOR RECIPROCAL MOVEMENT INTO AND OUT OF BATTERY POSITION, A TUBULAR HOUSING EXTENDING FORWARDLY FROM THE RECEIVER TO SURROUND SAID BARREL IN SPACED RELATION THERETO, A HOLLOW CYLINDRICAL DRUM ROTATABLY MOUNTED ON SAID HOUSING IN AXIAL COINCIDENCE WITH SAID BARREL THEREIN, A FOLLOWER PROJECTING OUTWARDLY FROM SAID BARREL, CAM MEANS IN THE INTERIOR OF SAID DRUM ENGAGEABLE WITH SAID 